"Olsborg Castle, Olofsborg"@en . . . "1503 or 1504" . "Olsborg Castle (Swedish: Olsborg), also Olofsborg, was as a fortified castle located in Tanum Municipality, Sweden, in the province of Bohusl\u00E4n. It is located on a steep cliff, and might previous to later use been an early hill fort. It was constructed in 1503 or 1504 by the squire Nils Ragvaldsson from \u00C5by, after a recent Swedish attack on Viken."@en .